Legend Has It:

Never change your bed on Friday.

Many cities do not have a 13th Street or a 13th Avenue.

Many buildings do not have a 13th floor.

According to folklorists, the earliest known documentation regarding “Friday the 13th” superstition occurred in an 1869 biography of Gioachino Rossini. Like so many other Italians of his time, Rossini regarded Friday as an unlucky day and the thirteen as an unlucky number. Ironically, Rossini died on a Friday the 13th in November.

Because most of the folklore was passed on by oral traditions, there is no way to determine the exact time or reason the superstition became so popular. Consequently, there are several theories which have been proposed to be the origin of “Friday the 13th.”

One theory states that it is a modern amalgamation of two older superstitions: one that thirteen is an unlucky number and that Friday is an unlucky day. In numerology, the number 12 is considered the number of completeness, as it relates to the 12 months of the year, 12 signs of the zodiac, 12 hours in a clock, 12 gods of Olympus and 12 Apostles of Jesus – the number 13 was considered irregular, transgressing this completeness.

There is also a superstition, thought by some to derive from the Last Supper or a Norse myth, that having 13 people seated at a table will result in the death of one of the diners. It has also been suggested that Friday has been considered an unlucky day because, according to Christian scripture Jesus was crucified on a Friday.

The Canterbury Tales, and many other professions have regarded Friday as an unlucky day to undertake journeys or begin new projects. And since the 1800’s Friday has been associated with other disasters, including the stock market crash, which resulted in the phrase “Black Friday.”

On the other hand, another theory by author Charles Panati, one of the leading authorities on the subject of "Origins" maintains that the superstition can be traced back to ancient myth and also to be a tale in Norse mythology. Friday is named for Frigga, the free-spirited goddess of love and fertility. When Norse and Germanic tribes converted to Christianity, Frigga was banished in shame to a mountaintop and labeled a witch. It was believed that every Friday, the spiteful goddess convened a meeting with other witches — a gathering of thirteen — and plotted ill turns of fate for the coming week.

On Friday the 13th of October 1066, King Harold II decided to go to battle on Saturday the October 14th, rather than allow his troops a day of rest (despite his army having made a long and arduous march from a battle near York just 3 weeks earlier). This decision to go to battle before the English troops were rested resulted in the loss of the battle by the English and King Harold was killed. This further established "Friday the 13th" as an unlucky day.

Another theory about the origin of the superstition traces the event to the arrest of the legendary Knights Templar. The connection between the superstition and the Knights Templar was popularized in the 2003 novel The Da Vinci Code. However, some experts think that it is relatively recent and is a modern-day invention.

According to the Stress Management Center and Phobia Institute in Asheville, North Carolina, an estimated 17 to 21 million people in the United States are affected by a fear surrounding “Friday the 13th” superstition. Some people are so paralyzed by fear that they avoid their normal routines in doing business, taking flights or even getting out of bed. Research further reports that it has been estimated approximately $800 or $900 million is lost in business on this day.

Even though we really have no way to pin-point the true origin of our superstitions surrounding “Friday the 13th” clearly there has been an impact on people across the world – in fact it has a clinical name: Paraskevidekatriaphobics (people afflicted with a morbid, irrational fear of “Friday the 13th”). So whether your believe in superstition or not, enjoy this week's "Friday the 13th"!